As far as the Applicant knows, no processes have been described so far, which are suitable for directly preparing polyfluorinated or perfluorinated derivatives of the ethereal type containing only the functionality of sulphonic nature, starting from compounds containing other reactive groups and/or functionalities, for example estereal, ethylenic etc. functionalities.
As is known, the simultaneous presence of other functionalities renders the product chemically less stable.
U.S. Pat. No. 2,732,398 describes a process for obtaining perfluoroalkylsulphonic derivatives, which are chemically inert, by direct electrochemical fluorination of alkylsulphonic acids.
Also the synthesis of polyfluoro-alkoxy fluorosulphonic compounds, containing hydrogen and/or halogens other than fluorine is known (see Inorganic Chem. 1987; 26; 2307; 2604).
However, these are processes which can neither lead to the preparation of the compounds forming the object of the present invention, nor give useful hints to this purpose.
In particular the process described in U.S. Pat. No. 2,732,398 leads only to the obtainment of perfluoroalkyl sulphonic compounds and it cannot be applicated to the perfluoroalkoxysulphonic compounds forming the object of the present invention.